Exhaust manifold bolts

[flonly]

Headed to see mr hagg to fix broken exhaust bolt.My question is should I use cummins bolts or some type of better aftermarket bolts.The reason I am asking this is motor was inframed exactly 2 years ago and about 170000 miles .Exhaust temps never go above 500 degree according to installed guage.I am assuming they were tourqed correctly when done by mr hagg .Why would one break in this short time and what can be done to prevent this in the future.

[Signature620]

They usually break because the manifold expands and adds shear pressure to the bolts on #2 & #5. The solution is to drill out the holes in the manifold on those two cylinders - I can't remember what size. If it broke a bolt on a different cylinder then it may just be a case of corrosion getting to them.

[Mr Hagg]

Yeah and we used new bolts ......I am not aware of any other aftermarket bolts.. But i will check into the drill out the manifold idea

[Magard]

It has the sleeves around the bolts... right? That’s supposed to be for absorbing expansion. Maybe the sleeves are work hardened and not allowing for expansion anymore.

[Signature620]

After some hunting I found it - TSB120263

https://quickserve.cummins.com/qs3/pubsy...20breakage

Drill the holes on #2 & #5 to 13.5mm or 17/32.

[Rawze]

that would be this reamer...
https://www.mcmaster.com/3106A43

I reem them whenever someone is here and the manifold has to get removed for some reason or another.

I also take it over to a local machine shop nearby, they have a large belt sander big enough to for the whole manifold to sit flat on it, can put the whole manifold on it, clean its mating surfaces up evenly while removing distortion.

Tags:

TSB, exhaust broken bolts, exhaust manifold bolts broken, exhaust manifold reamer, exhaust manifold reemer, isx exhaust manifold, 17/32

[Silverwolf]

Bolts are probably fine stock. But ARP makes the best bolts on the planet. Never had one fail yet.

[Mr Hagg]

Ivehad the arp bolts brake on the C15 acert engines